Fix share link download counter incrementing before file existence check (#146)

The download counter was incremented before verifying the shared file
still exists in the bucket. If the file was deleted, accessing the share
link would increment the counter and eventually exhaust the download
limit without any actual downloads. Move file retrieval before counter
increment so the count only increases on successful downloads.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: G4brym

.changeset/fix-share-download-counter.md

@@ -0,0 +1,5 @@
+---
+"r2-explorer": patch
+---
+
+Fix share link download counter incrementing before verifying file exists. Previously, if the shared file was deleted from the bucket, accessing the share link would still increment the download counter before returning a 404 error. This could exhaust the download limit without any actual downloads occurring. The counter now only increments after confirming the file exists.

packages/worker/src/modules/buckets/getShareLink.ts

@@ -111,7 +111,16 @@ export class GetShareLink extends OpenAPIRoute {
 			}
 		}
 
-		// Increment download counter
+		// Get the actual file before incrementing counter
+		const file = await bucket.get(shareMetadata.key);
+
+		if (!file) {
+			throw new HTTPException(404, {
+				message: "Shared file not found",
+			});
+		}
+
+		// Increment download counter only after confirming file exists
 		shareMetadata.currentDownloads++;
 		await bucket.put(
 			`.r2-explorer/sharable-links/${shareId}.json`,
@@ -125,15 +134,6 @@ export class GetShareLink extends OpenAPIRoute {
 			},
 		);
 
-		// Get the actual file
-		const file = await bucket.get(shareMetadata.key);
-
-		if (!file) {
-			throw new HTTPException(404, {
-				message: "Shared file not found",
-			});
-		}
-
 		// Return the file with proper headers
 		const headers = new Headers();
 		file.writeHttpMetadata(headers);